Let me explain. I have bachelors in pure math (as opposed to applied math) and a bachelors and masters in nuclear engineering. I am employed as a nuclear engineer and I am happy. Before completing my masters, I did one semester of graduate work in math (I might still be there had I not taken combinatorics, differential topology, linear algebra, and complex analysis all in the same semester without the best background in math). But anyway, I would like to continue to learn math (in particular I would really want to learn more number theory), but I cannot go back to school. I was wondering what some of you think of my predicament, and whether you guys could supply either some ideas of how to complete some further study in graduate mathematics without, seemingly, the necessary resources. I would also be interested if anyone knows about some open course ware similar the the MIT program. Thanks!